Multiple-cylinder reciprocatory pump and fluid-actuated motor of the swash-plate type



Feb. 11, 1930. 3, BOYCE 1,746, 335

MULTIPLE CYLINDEERECIEROCATORY PUMP AND FLUID ACTUAIED MOTOR OF THE SWASH PLATE TYPE Filed Aug'. 24. 1928 Patented Feb. 11, 1930 REGINALD DONOVAN BOYCE, OF LONDON,

PATENT OFFICE ENGLAND, ASSIGNOR TO ROMAC MOTOR ACCESSORIES LIMITED, MIDDLE-SEX, ENGLAND H MUIiTIPLE-CYDINDER- RECIPROCATORY PUMP AND FLUID-ACTUATED MOTOR OF THE SWASH-PLATE' TYPE Application filed August 24, 1928, Serial No.

This invention relates to multiple-cylinder reciprocatory vpumps and fluid-actuated motors of the swash-plate type having the cylinders arranged around and in axial parallelism with a single rotary shaft, the object of the invention being to provide improved means for maintaining operative connection between the swashplate and the several pistons of the pump or motor, without the em ,ployment of connecting-rods, or of springs interposed between the pistons and a stationary abutment.

By the present invention, each piston is constrained to follow the coacting portion of the swashplate during the movement of said portion in a direction away from the corresponding cylinder, for which purpose, according to the invention means are provided for establishing operative engagement between the several pistons and both sides of the swashplate.

In order to ensure continuity of engagement between the pistons and that side'of the swashplate remote therefrom, and thus to obviate risk of chattering, such engagement may be established through the medium of elastic pressure. In one embodiment of the invention, each piston is provided with a rearward extension adapted to bear on the one hand directly against that side of the swashplate which is towards the cylinders and on the other hand against the opposite side of the swashplate through a springinfluenced member (such for example as a plunger) carried by but movable relatively to said piston-extension.

The accompanying drawings illustrate, by way of example, one form of multiple-cylinder swashplate air-pump constructed in accordance with the present invention; Figure are shown in the example) are arranged sym- 301,914, and in Great Britain June 5, 1928.

metrically around and in axial arallelism with a single rotary shaft 12 whlch is journelled in abearing 13 at one end of a casing 14: to the other end of which is attached the cylinder-block 15, the latter being bored to accommodate the single-acting pistons 16. Those ends of the cylinders which are towards the bearing 13 are open whilst their "opposite (or front) ends are closed in common by a cover 17 formed with two concentric chambers, whereof the inner chamber 18 is in communication on the one hand freely with the outer atmosphere at 18 and on the other hand with the respective cylinders 11 through non-return inlet or suction valves 19.. whilst the outer chamber 20 is in communication on the one hand with the respective cylinders 11 through non-return delivery valves 21 and on the other hand with a delivery pipe or passage '(not shown).

The shaft 12, which is furnished outside the casing 14 with a sprocket wheel 22 through which it receives rotary motion, has fast upon its inner end an oblique-faced cam-member 23, between the rear end of which and the adjacent portion of the casing around the bearing 13 is interposed a ball thrust bearing 24. The oblique front face of the cam-member 23 makes contact, through a correspondingly obliquely-disposed ball bearing 25, with the rear face 26 of a circular swashplate 26 centrally poised upon a ball 27 carried at the inner extremity of a pillar 28 extending, in axial alignment with the shaft 12, through the cover 17 and cylinder-block 15, wherein the pillar is adjustably supported by the outer portion 29 of its length being in screwthreaded engagement with a central hole in the cylinder-block. 29 is a lock-nut which engages the threaded portion 29 of the pillar and bears against the cover 17, the outer end of thisnut being open to afford access to the corresponding extremity of the pillar for the purpose of adjustment.

Each piston 16 has at its inner end a rearward axial extension 30 of reduced diameter, said piston-extension for resilient engagement the domed extremity 31 of which contacts with the front face 26 of the swashplate 26; whilst the piston-extension 30 also carries a substantially hook-shaped bracket 32 which extends, outside the periphery of the swash plate, to a distance beyond the rear face 26 of the latter; the rearward portion of the bracket 32, which overhangs the rear face of the swashplate, being formed with a socket 33 to accommodate a plunger 34; whereof the domed head or front end 35 contacts with said rear face 26. The plunger 34, which extends parallel to the shaft 12, is guided by passing at 36 through an aperture in the rear end of the socket 33, whilst a spring 37, coiled in compression between the bottom of the socket and the head 35 of the plunger, ensures continuous maintenance of contact (and con sequent elimination of chattering) between the plunger and swashplate under the constant variation occurring in the eifective distance between the heads 31 and 35 of the piston-extension and plunger owing to the wobbling movement imparted to the swashplate by the rotation of the cam-member 23.

It will be observed that the rearward or return stroke of each piston 16 is caused, as the corresponding marginal portion of the swashplate 26 moves rearwards, by the thrust transmitted from the swashplate to the plunger 34 and thence through the spring 37 and bracket 32 to the piston-extension 30.

In the example illustrated, each bracket 32 is formed at its front end with a collar 38 which fits around the slightly tapered pistonextension 30; the collar 38 being split and clamped in position upon the piston-extension by means of a screw 39 as indicated in Figure 2.

Where the invention is applied to a fluidactuated motor, a construction substantially similar to that illustrated may be employed, suitable provision for the supply and exhaust of motive fluid under pressure to and from the several cylinders being substituted for the valves 19 and 20 referred to in the foregoing description.

I claim i 1. A multiple-cylinder and piston reciprocatory pump or fluid-actuated motor of the swashplate type, having means for establishlng operative engagement between the several pistons and both sides of the swashplate, for the purpose of constraining each piston to follow the coacting portion of the swashplate during the movement of said portion both toward and away from the corresponding cylinder, wherein each piston is provided with an extension adapted to bear directly against that side of the swashplate which is towards the cylinders for positive thrust therebetween and against the opposite side of the swashplate through a spring-influenced member carried by but movable relatively to 

